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The Heating Engineers of Winterfellhttps://jesseemspak.com/2016/06/23/the-heating-engineers-of-winterfell/
https://jesseemspak.com/2016/06/23/the-heating-engineers-of-winterfell/#commentsThu, 23 Jun 2016 15:00:00 +0000http://jesseemspak.com/?p=254Continue reading →]]>In Game of Thrones Winterfell is a large castle that is built on a set of hot springs that provide warmth and even keep the castle comfortable during the years-long winters that characterize the region. The hot springs also warm a greenhouse, which provides food when the fields are fallow.

But how does this work, exactly? And can a greenhouse provide enough to feed the population of a small town or keep?

Hot springs were known in both the classical and medieval worlds. Towns sprung up around them, as people went for their supposed health benefits. (In modern Germany, many health insurance companies will even pay for a visit to a spa).

There is in fact, a town in France that got its entire hot water supply from hot springs – Chaudes-Aigues. The original system was built in the 14th century, supplying hot water to homes with simple wooden pipes. In that case the sources were upstream of the village, so it was gravity fed. The water comes out at about 82 C (179 F) which is a lot hotter than most homes (which are about 48 C, 120 F).

Historical castles weren’t often built on or near hot springs, mostly because the springs didn’t happen to be in important enough locations. Remember castles were a military installation first. But it’s not hard to imagine that in Westeros, Winterfell happened to hit a spot that was strategically important.

So how would a medieval stonemason work out an in-wall heating system? The Romans made pipes of lead, and the technique for making them out of wood and other materials was certainly available to medieval people. Clay pipes were known as early as Babylon. Contrary to popular myth, the Romans weren’t sickened in by lead poisoning from the pipes, because the local supplies had a lot of calcium in them. If you live in London or Los Angeles you’ve seen the effect on your tea kettle: scaling. Calcium carbonate formed on the insides of pipes, and that actually kept a lot of the lead out of the water. The lead poisoning the Romans got was largely due to lead as a food additive to wine and the use of lead implements in cooking.

As for pumping, medieval engineers were familiar with the artesian well, which was worked out in the 12th century (the name comes from the region of Artois). If the hot springs of Winterfell are heated geothermally, and the water recharges a local aquifer, it’s not inconceivable that near the source, the water would emerge at relatively high pressures. (The good people over at Generation Anthropocene have an outline of the geology of the hot springs, which may resemble those of California).

It’s unclear from the books whether the people in Winterfell or the local Winter Town drink the hot water; that from Chaudes Aigues has a lot of salt in it – as much as 5.9 grams per liter –and wouldn’t taste very good. The geothermal water in many parts of California isn’t really potable either.

So we can imagine an early architect of Winterfell seeing some local hot springs, and either using the pressure of the spring itself, piping the water downhill (if there is enough elevation) or digging an artesian well.

The walls that are heated only have to be in the parts of the castle where people live. According to a Wiki of Ice and Fire the Great Keep is the part of the structure built over the hot springs. Besides, there’s no good reason to pump water through the outer curtain walls, nor storage areas. So it is perfectly feasible to imagine Winterfell’s builders – perhaps Bran the Builder himself – designing a keep with thick outer walls for both defense and to keep the heat of the hot water in, and a thin inner wall to allow the heat to radiate out. That designer may have even set the system up as loops of pipe (or even simply openings in the stone, similar to the Roman design for many aqueducts), allowing water to flow downward after it has cooled, and then back to the hotter water that comes from the spring – a giant primitive heat exchanger. A medieval technician, if the person remembered Roman-like technique, could certainly build something to supply Winterfell with hot water.

Also, if you want to keep a room warm, you needn’t heat it that much. Assuming a water temperature like that of Chaudes-Aigues, one could imagine walls radiating heat that is enough to keep a room pretty comfortable. Old-fashioned steam radiators were of cast iron, and they could keep a room at 70 degrees.

Doing some simple modeling, and assuming that the heat conduction for granite,is about what it is for Scottish granite (Per Wikipedia), and a wall area of about 10 square meters, 10 centimeters thick, and the temperature difference of 82 C (basically heating up a room from freezing), the total heat loss would be on the order of 3800 Watts, which is plenty to heat a room four meters on a side.

But what about food? Winters are years long, and that means you need foods that keep in a cellar or storehouse without rotting (to say nothing of the problem of vermin).

Winterfell has a greenhouse. As far back as the 13th century Italian lords built botanical gardens. And the Romans had the technique of planting cucumbers and leaving them outside to get the sunlight while bringing them in at night. Romans architects and engineers also occasionally used selenite, a transparent mineral, as a kind of transparent windows. Medieval churches are, of course, full of stained glass. So greenhouses were possible with medieval-level technology.

Let’s assume Winterfell has a garrison of some 200 people – originally the Stark family, plus their most trusted retainers and knights. (Ned Stark took a contingent of about 100 people with him to King’s Landing, and that was a sizable part of the castle’s manpower). In actual medieval castles most of the people working there didn’t actually live in it unless there was a siege, but George R. R. Martin has the Winter Town outside the walls, so we can assume that the castle might also have served to store provisions for the long winters. He doesn’t say how big the Winter Town is, but most medieval towns were small, and the North is said to be sparsely populated.

A greenhouse doesn’t need to be quite so large; if the purpose is to provide supplemental fruits and vegetables. But heat isn’t the only thing that plants need; they require sunlight as well. Many herbs, for instance, won’t grow well at all unless there is a solid six hours of sunlight at least. It isn’t clear if in the world of Game of Thrones that the nights get longer in the winter, though there is some indication that they do. If so, the greenhouse won’t be as much help as it might be.

A single person eats about a pound of wheat per day (this is about what it takes to make a loaf of bread), so that’s about 365 pounds a year. So to feed a village of 5,000 people would require some 1.82 million pounds of wheat per year. A bushel of wheat weighs in at about 60 pounds, and that means about 30,400 bushels, or on the order of 37,000 cubic feet of space. That fit in a room about 40 by 20 by 50 feet (extrapolating from numbers here).

That isn’t a lot of space given the size of the castle of Winterfell, which covers an area hundreds of yards on a side. So it’s not hard to picture storing enough food for thousands of people for two years or more. Wheat stores rather well (most plant seeds do) as long as they are in relatively cool (but not too cool) conditions. A storage area that can be kept above freezing should do it.

However, wheat isn’t the only food available. Martin also posited potatoes as part of the Westerosi diet. Potatoes store for months in a root cellar, and even when they start to sprout a bit you can simply cut those parts off before you cook them.

Other vegetables don’t store so well – tomatoes, for example, can be dried and last several months, but not years. This is where the greenhouse comes in. If you wanted to use it as a supplement to the bread, porridge and boiled potatoes during the winter, it might just work. The “glass garden” dimensions are never explicitly stated. But roughly speaking if the glass gardens cover a hectare (10,000 square meters, or 0.4 acres) it’s possible to grow enough vegetables on a rotating basis to at least supplement the diet of the garrison in the castle itself. Even with relatively primitive farming methods one could plant the whole greenhouse with about 3,000 tomato plants, for example, which is enough for a lot of people to eat. On a rotating bass one could plant onions, which last a couple of months with good storage conditions, or carrots, which last anywhere from two to seven months in a root cellar.

Looking at the shelf life of most vegetables, though, it seems pretty likely that once winter sets in, a greenhouse would have to have a pretty rapid rotation of crops, though there’s a lot of leeway depending on the vegetable. It also depends on the sunlight; even if the temperature is right it is hard to get crops to grow right absent enough light. So if in Martin’s world the winter days are shorter the population of Winterfell is going to have some problems even with a greenhouse. Essentially, the diets in Winter Town are going to get mighty boring once winter gets into year two.

That said, home grown food isn’t the only option. According to the histories mentioned in Martin’s work, the southern Westerosi regions did have some food surpluses even in winter; the seasons might be years long but they don’t grip the world in an ice age, either. So it’s certainly possible for Winterfell to import some food. That would be crucial; even with years of shelf life for wheat and other grains, any winter that pushed the five year mark would be a real problem for the people of the North.

While we seem to have solved some problems of heating and feeding Winterfell, it’s useful to ask why medieval engineers never did this. The reason is that in some ways it is a problem in search of a solution. One of the big medieval innovations in home heating was the fireplace and chimney. Putting a fire up against a thick outer wall, surrounding it with stone that could re-radiate the heat, while the smoke and soot went out the chimney, worked very, very well and was far superior to the previous system of putting a hearth in the middle of the room. It’s also a lot simpler to build. Castles were first and foremost military installations, not homes. The fanciful castles of Germany like Neuschwanstein were mostly built in the 19th century.

This is also ties into why greenhouses, though they were known to people of the period in basic forms, were rare. The great botanical gardens of Spain (as in Seville) and Italy were usually outdoors, rather than enclosed. Clear glass in large sheets was devilishly hard to make – the pieces that make up a stained glass window are relatively small. So if you built a greenhouse it would probably not have the huge panes we associate with modern designs. And while selenite can substitute for glass, selenite is a crystal, and very hard to cut into sheets.

Window glass, in fact, remained something of a luxury all the way to the 17th century. Enclosing an area of any size in glass would have been a hideously expensive project to any lord or king of the middle ages, even allowing for glass that wasn’t clear.

Note: this post was edited to reflect that Artois is a region, not a town.

——————-

If you liked this post, and like Game of Thrones, check out the following Game of Thrones science posts as part of this week’s GoT Science Blog Carnival:

Game of Thrones is back, and with it Valyrian steel swords. Magic or otherwise better-than-normal swords are common to fantasy literature, and it got m thinking about the real-life basis for it. There is one, and it doesn’t even require magic: Damascus steel, the scourge of medieval and early modern warfare.

Let’s give credit where credit is due: the idea came from this video that gets into the possibilities of Valyrian steel, which comes at it from the point of view of pure chemistry and metallurgy rather than archeology. So apologies to Ryan Consell.

Let’s start with the properties of Valyrian steel. In the books Valyrian steel is harder, holds an edge better, and lighter than any ordinary steel used in swords or knives (George R. R. Martin isn’t clear as to whether it is ever used for armor, though it isn’t inconceivable).

When Jon turned the sword sideways, he could see the ripples in the dark steel where the metal had been folded back on itself again and again…” (Game of Thrones, chapter 60 [Jon])

This is a strong clue. The folding is known in the business as pattern welding, and Damascus steel was made in just this way. The name comes from the city of Damascus, where the swords were purportedly made. Odds are they were manufactured all over the region and Damascus was just the place where the people selling the swords tended to be from (Europeans who went there were never all that particular about details).

What makes pattern welding so powerful is the folding. Steel of any sort is a combination of iron and carbon. Stainless steel, spring steel and structural steel all have differing amounts of carbon in them depending on what you want from the metal. The amount of carbon is pretty small, usually less than 1 percent, but combine that with other trace elements and you can get an alloy that has whatever properties you’re looking for. In the case of spring steel, for instance, you want something that retains its shape, and for flatware you’d want the metal to resist corrosion.

In the case of swords, you need a metal that is resilient, but will also hold an edge. A sharp sword that is hard but shatters when it hits something isn’t much use. Pure iron, though, is too soft and vulnerable to corrosion. That’s where the pattern welding comes in. By alternating layers of relatively soft, low-carbon steel with layers of higher-carbon steel, you can get the best of both worlds. The quenching (with water, but there are accounts of smiths using other liquids such as oil and even blood) also alters the metal – carbon steel gets harder.

Pattern welding is such a useful method that it was invented independently at least three times. Celts in Europe hit on it sometime around the birth of Christ, and Indian smiths figured it out even earlier than that, probably around 600 BCE. Japanese sword makers used a form of it from an early age as well, and probably got the technique from Chinese smiths around 400 BCE. Pattern welding is labor-intensive, so European smiths seem to have left off the technique by the middle ages, perhaps because homogenous steel weapons were easier to mass-produce. Recall that Europe, like Westeros, was a mass of local kings and petty lords vying for dominance, and that would create pressure to make lots of weapons fast. Whatever the reason, by the time the Crusades are happening the place to get a Damascus steel sword was in the Ottoman Empire and points east.

Damascus steel involved more than technique. The raw material itself was blocks of wootz steel, which was invented in India. Wootz steel was near legendary in its day, and the Indian smiths were renowned the world over for their metallurgical skill. The secrets of making it were lost some time in the 18th or 19th century, but modern archeologists have done a pretty good job of figuring out how it was likely done.

Wootz steel gets its combination of resilience and hardness from trace elements and compounds. One of these is called cementite (Fe3C). Modern researchers think that the traces were due to where the iron was mined and the kind of carbonizing process the Indian metallurgists used. Older accounts speak of the use of specific tree species to be used to make the charcoal used in adding carbon to the iron, and specific mines. There might have been other metals, such as vanadium or cobalt, for instance, that the preindustrial craftsmen would have been unaware of.

Another fascinating piece of evidence for the “secret” of Damascus steel was found in 2006. A team at the Technical University of Dresden found, after examining a blade with an electron microscope, that there were carbon nanotubes in the steel. The nanotubes facilitate the formation of cementite wires, at the nanometer scale, inside the steel.

So how good was a Damascus blade? Legends abound of Damascene blades cutting hairs dropped on them and cutting off limbs with one stroke. I’d not buy the hair splitting trick, but a good blade in the hands of a skilled user can accomplish a lot. (If you doubt that something weighing what a sword does can cut through a limb, pick up a meat cleaver and break down a chicken. Now imagine something that’s twice as heavy smacking into your collarbone. Ouch!).

It’s also important to remember that in warfare, sometimes even a marginal technical improvement means a lot. Damascus blades were expensive to make, but when the European knights met their Ottoman opponents during the Crusades they were pretty (unpleasantly) shocked. That in turn created a market for such blades in Europe. I suspect the Damascus swordsmiths weren’t too unhappy – profits were profits. And while a very skilled smith might be able to repair or re-forge a Damascus blade, it was pretty unlikely that any Europeans would have learned to make them from scratch.

All this fits pretty well with the picture of Valyrian steel: a metal made by a group of artisans whose technique has been lost (or who can only be trained in a city very far away) with properties that seem superior to anything local blacksmiths can match. Even the patterning and the color seem to fit, and there’s no need to invoke magic, or knowledge that a pre-industrial people wouldn’t have.

Of course, the final authority is the man himself, George R. R. Martin. He says the Valyrian freehold used magic, and who are we to say otherwise?

References:
The Mystery of Damascus Blades, by John D. Verhoeven, Scientific American, January 2001.

By Multimotyl (Own work), via Wikimedia Commons

The recent revelation (via a class-action suit) that some cheaper wines have high levels of arsenic got m to thinking: how toxic is it, really? And is it as dangerous as we think?

I’m not one to say that stuff like that in wine is a good thing. I’m a wee bit of an oenophile myself, though I strongly advocate staying under $20 for a good bottle for most occasions.

So the question is, if wine has arsenic in it, how much are we getting when we drink it, and how that compares with water from the tap.

First let’s look at how much was in the wine. According to this story, the highest arsenic levels were 50 parts per billion in one bottle (out of 1,300) that was tested. On average the levels were 30 parts per billion. The standard for drinking water is 10 parts per billion.

One part per billion is equal to one gram of arsenic in 1 million liters of water, which is enough to fill a “short course” 25-meter swimming pool. Not much, but arsenic is damned toxic stuff.

A lethal dose is 2-20 milligrams per kilogram of body weight, which means that someone weighing about 75 kg (or 165 pounds) would die if they ingested as little as 150 milligrams of arsenic as arsenic trioxide (As2O3). Arsenic trioxide is an odorless and tasteless white powder made famous by pre-modern assassins because it dissolves in water. Among the victims were a Chinese Emperor and Francesco I de’ Medici.

Arsenic was a great poison because the symptoms, abdominal cramps and vomiting, might be food poisoning or a lot of other things — in pre-modern times there really was no way to test for it.

However, let’s be clear: 150 milligrams is a lot compared to what’s in a bottle of wine, even at the highest levels. At 50 ppb in a 750 milliliter bottle, that’s 3.75 × 10-5 grams of arsenic (I assumed that wine weighs as much as water does, though it’s probably a wee bit less because of the alcohol), or 0.0375 milligrams – a tiny portion of the minimum lethal dose.

Does this mean there is nothing to worry about? Not quite. Arsenic is dangerous in water supplies because it can cause cancer over time. It is a problem in New England wells, as studies showed higher bladder cancer rates where people drink from wells. One scientist described it to me thus: a map of bladder cancer cases in New England “lights up like a Christmas tree” that neatly maps out areas where most people drink from local wells, where naturally occurring arsenic leaches into water from the surrounding rock. (The problem is much reduced for people on municipal water supplies because the water comes from reservoirs and rivers).

There’s some dispute, though, over how much arsenic causes elevated cancer rates – a study from Taiwan seemed to show that 150 ppb was the point that cancer rates went up, and that’s higher than other studies from the U.S. On the other hand it’s possible that prolonged exposure over generations makes people tolerant, as might have happened to a group of Native people living in the Atacama desert.

How much arsenic is someone who drinks the cheap bottle of wine with 50 ppb in it getting over time? For that you have to look at how much wine they are drinking. One of the reasons arsenic standards for drinking water and wine (or other beverages) are different is simply that people drink more water. Unless you have an alcohol problem like Tyrion Lannister you probably aren’t drinking wine every single day.

The Wine Institute says Americans drank some 779 million gallons of table wine in 2013. That works out to 2.94 billion liters. If all that wine had 50 ppb of arsenic, that’s 147 kilograms of arsenic spread among 300 million people, or just about 0.49 milligrams of arsenic per person per year. That’s less than a quarter of a minimum lethal dose ingested in a whole year.

Now, that calculation (as many will point out) doesn’t take into account that every man, woman and child in the US isn’t drinking wine. But even cutting down the number of people by a factor of four means that on any given day there just isn’t that much arsenic going into our collective systems from wine.

Put another way, if you drink that bottle of 50 ppb wine all by yourself it is far from enough arsenic to kill you. If you drank one of those bottles every single day you’d get to a lethal dose in about three months – assuming your body retained all the arsenic, which it doesn’t.

The real concern is long term consumption. So people drinking cheap wine for several years running might be at higher risk for certain cancers. An interesting study would be looking at areas where Two Buck Chuck sells well and then looking at bladder cancer rates. You’d have o factor out the drinking water – arsenic levels are high in well water in the American West, and then track the bladder cancer rates over time.

And if I were to throw out a hypothesis, the reason for high rates of arsenic might be the soil where the wine is grown. If arsenic levels are high in well water in parts of California where wine grapes are cultivated, then one would expect some of that to show up in the plants that grow there also. A map of arsenic levels here shows a little bit of correlation – the stretch near Lodi and in Napa has a higher-than-normal concentration of arsenic in the water. But that doesn’t mean the grapes used in the wines tested for arsenic came from there. It’s suggestive though, and if anyone has any real studies on the topic I’d love to know.

There’s no reason to be drinking more carcinogens than you have to, and arsenic is pretty rough stuff. But it’s important to add a little perspective. If you drink water from a private well and live in Maine, odds are you’re getting far more arsenic that way than from the wine you got at Trader Joe’s.

Recently Discover, Mother Jones, the Washington Post, and many corners of the blogosphere have gone over Bill Nye’s change of heart about genetically modified crops. Originally, Nye’s skepticism carried a lot of weight – he is “the science guy” after all.

Here’s the thing though. The whole discussion about GMOs is often about GMOs as technology as though it were completely divorced from the system in which it is produced. I am not going to dispute that they are safe to eat. They are, full stop (or at least they aren’t any more dangerous than a lot of other stuff).

Nor am I going to push too hard on the environmental front just now, though I am skeptical that anyone has worked out the unintended consequences.

Mother Jones asked (rhetorically) is what Monsanto showed Nye that made him change his mind. I’d say that the science of what Monsanto showed him was sound and they satisfied him that the technology was fine.

I think the issue, though, is not one of technology or even science. It is something that Nye brought up at the very start.

Also, we have a strange situation where we have malnourished fat people. It’s not that we need more food. It’s that we need to manage our food system better.

So when corporations seek government funding for genetic modification of food sources, I stroke my chin.

I myself find it exciting that you might be able to do all sorts of things with plant biology. But the issue for me — and a lot of other critics — is when GMOs are touted as the solution to global hunger and food shortages, to the near-exclusion of anything else.

The problem with GMOs is that they can let us paper over very real problems. So we go on doing things that simply aren’t sustainable to begin with. More to the point, they let us keep social systems in place that are actively harmful. They are a technological solution to a non-technological problem.

Golden rice is great – but I want to know why we need to tack on vitamins to the rice at all. I want to know why it is the people we are selling this to can’t get the other foods they need. I submit that it isn’t some magical inevitable consequence of civilization, it’s a direct result of decisions we make about how we organize society. Vitamin A deficiency is a huge problem in the developing world. But it isn’t like people there are so dumb that they wouldn’t buy vitamin A-rich food if it were affordable. If the population is only paid enough to buy rice and nothing else, then it doesn’t matter how nutritious the rice is — there’s a social structure problem that needs to be addressed.

This isn’t the first time this has happened. Another crop, the potato, a “naturally” made GMO, presented the same kinds of problems in the 19th century.

Potatoes are a pretty miraculous crop. Thousands of varieties exist, and at least one study posits that the tuber was responsible for a pretty large fraction of population growth in Europe after 1700. A single potato has all the vitamin A, more than half the iron and vitamin C, and nearly a third of the calcium a person needs. There’s lots of starch and some of it is as good as fiber.

A miracle, indeed. In fact, potatoes can be grown on much less land than any crop of its kind, in a really wide variety of climates. By any standard that’s a win, right? Well, not in Ireland.

Most people know that the Irish potato famine was caused by monoculture, and the vulnerability of a particular type of potato (called the Irish Lumper) to blight and a lack of genetic diversity.

The problem, though, did not start there. Potatoes were a technical solution to the problem of growing food for a rising population of mostly tenant farmers. But its success was a problem in itself: the Irish dependence on it increased precisely because it was such a good crop for small plots of marginal land.

With wheat, there was a lower limit to how much land you could put an Irish peasant on. That is, too little land and the peasant starves, and dead people don’t pay rent or provide labor. To provide for a well-rounded diet a family of four needs at least two acres, but in Ireland in the 1840s a quarter of the farms were less than that. That left potatoes as the only crop that would provide enough calories. Potatoes are great in this regard; you can live almost entirely on potatoes and milk, and many people did. Pushing the farmers to smaller lots (which increased the rent revenue to the estates) put more pressure on tenant farmers to move to monoculture of potatoes, precisely because of their nutritional value.

The tenant farmers had few or no rights to the land they worked, which dis-incentivized capital improvements. At the same time the absentee landlord system rewarded cutting landholdings into small pieces and renting it out to as many tenants as possible — and pushing those tenants onto marginal plots so the rest could be used for cash crops or livestock (cows and sheep in particular).

The plants, though, worked. From a purely technological perspective the potato was a success. The issue was political — how to organize the land economy in Ireland. Potatoes were an enabling technology, they just enabled the wrong thing. The result was a system that was unsustainable, and vulnerable to the slightest ecological shock. The blight provided one.

And that’s the problem I have with GM crops. I don’t doubt that Bt corn and Golden Rice and whatever else can do all the things that the companies that make say it can. But whether GM crops are physically capable of certain things is the wrong question. What’s necessary is a re-think of how we organize society, and why we distribute food in such a way that such crops are even necessary.

This isn’t just a question of GM crops. It’s a whole outlook that favors technological solutions that I and a lot of other people are calling into question. Technology can do great things, but it is not independent of the social system we live in.

I’m not against GM research. I am against using GM crops as a way to keep doing something that is unsustainable, and locking in social relations that create the very problems GM crops are supposed to solve.

In that sense Bill Nye’s original question – and skepticism – is still relevant.

]]>https://jesseemspak.com/2015/03/06/bill-nye-was-right-the-first-time/feed/0jesseemspakFermi Paradox Part III: Why Aren’t They Here?https://jesseemspak.com/2015/01/30/fermi-paradox-part-iii-why-arent-they-here/
https://jesseemspak.com/2015/01/30/fermi-paradox-part-iii-why-arent-they-here/#respondFri, 30 Jan 2015 18:51:21 +0000http://jesseemspak.com/?p=91Continue reading →]]>
A Bussard ramjet, one of many designs for a true interstellar spacecraft. Ramjets wouldn’t go more than a fraction of the speed of light. By NASA [Public domain], via Wikimedia Commons

This is the third in a series of three posts I did on the Fermi Paradox, starting with some numbers from over at the Planetary Habitability Laboratory. In the first two I wrote about why alien civilizations would be hard to see, either via radio waves or Dyson projects. In this one I will get into the numbers behind planetary colonization and what that says about the odds that there’s anyone out there.

I’ll do two things. First is a look at the mathematics of interstellar colonization – how long could we reasonably expect it to take for a civilization to fill the galaxy? The second is to use a little data on the distribution of stars in the galactic habitable zone to see how likely it is that there’s anyone around currently.

Picture a civilization that sends out starships, and let’s say they have a massive colonization program. They send out a whole fleet, to the nearest 10 habitable planets. That will fill a sphere of about 10 light years, assuming that there’s an average distance of about 10 light years between planets. (I work out the numbers here and the PHL has theirs here). Then, let’s say it takes a century for the colony worlds to send out their own ships. Another 10 each, so you get 100 going out. We will further assume that these ships go at just a hair under the speed of light.

That would get us to a sphere with 110 habitable worlds, and it would be 20 to 22 light years wide. It would take a total of 120 years to fill that up. The next step we have 1,100 ships going out, filling a sphere about 150 or so light years wide. But note how much bigger that sphere is; the ships will take about another 130 years to get to the edges. So in year 450 of the colonization era the next batch of ships goes out but it will take them 1,000 years or so to fill the next spherical shell of planets.

Note that the rate of increase in the size of the colonization sphere starts to slow down, and become linear. Eventually, we see that it takes about 100 million years to colonize the whole galaxy, because it’s 100,000 light years across and nothing can go faster than light. (This assumes that one of the colonization “lines” goes straight across).

Think about that span of time – a 100 million year old society, appearing in our solar system now, would have been starting in the Cretaceous. They’d have been launching Apollo missions 40 million years before the famous Tyrannosaurus Rex had even evolved.

This also assumes a pretty brisk schedule of launches. It assumes that people keep on building and building and never, ever stop. I’d say it’s likely that any colonization effort would take a lot longer.

But out of millions of civilizations, wouldn’t somebody make it to the 100-million-yar anniversary?

Possibly. Here’s where we can look at an old idea called the Drake Equation. Formulated by Frank Drake, it was more of a thought experiment than anything else. But it’s a useful way to quantify what you don’t know, as they say. It looks like this:

N = R*ƒp ne ƒl ƒi ƒc L

R*= the rate of star formation (stars per year)
ƒp = the fraction of stars with planets
ne = the number of planets per star that can support life
ƒl = the fraction that develop life to begin with
ƒi = the fraction that get to intelligent life
ƒc = the fraction that develop a technical civilization that can send radio signals
L = the length of time they send signals or exist, in years

ƒl , ƒi , ƒc , and L are all unknowns. So let’s come up with some reasonable values.

Life showed up on Earth almost as soon as conditions allowed it. To be really generous, we will assume it’s 1. That is, every habitable world will have something alive on it at some time. Maybe it’s bacteria or lichen but it’s alive.

ƒi is one that we’d be more conservative on. The reason is there’s no reason to think intelligence is a natural and inevitable consequence of complex life. Yes we are here, but look at how few intelligent species there are, given how many we share the planet with. Then consider how many species have come and gone in the last 3 billion years. It probably amounts to billions – after all there are at least a million species of insect around right now.

And of all those species, only a few got smart enough to make and use tools. Even restricting ourselves to considering families of animals, or orders, the evolution of tool-using and manipulation of the environment in the way humans do seems to be exceedingly rare. The late Stephen Jay Gould might have been wrong that the Burgess Shale fauna represented new phyla of animals, but he was probably right that nothing like a human would be likely if we replayed Earth’s history, given the sort-of-random nature of evolution.

That appears to indicate that ƒi is very, very small, on the order of 10-8 or 10-7– one in a hundred million, or on in ten million, even assuming every smart animal develops a technical civilization.

Then we get L. This is dicey, we only have our own civilization to go on, and we might destroy it (at least it’s ability to get into space) darn fast. We’ve only had such a civilization (radio and space-capable) for 100 years or so. Heck, the whole human species (Homo Sapiens in this case) has only existed for 100,000 years at the most. As a fraction of planetary lifetime that is very, very small.

Recall the Drake equation. Using the values we guesstimated earlier, and assuming a civilization lasts or 100 million years,

N = (7)(1)(2)(1)(1/10,000,000)(1)(100,000,000) = 140

That isn’t many. It would put civilizations at about 5,000 to 7,500 light years apart on average, depending on whether you exclude a big chunk of the galactic center and its environs. Since the galactic center is probably too chaotic (lots of supernovae and crowded stars that mess up orbits) we can go with the lower figure.

Using the calculation at the beginning of the post, that means about a half a million years for a group of smart aliens to run into another group of smart aliens. Working from that, it would still seem they should be here.

That, I think, provides evidence that civilizations are simply rare. There is, however, another factor we need to think through. Not all civilizations will form at the same time. Some might have come and gone millions of years ago. So maybe intelligence and space travel are common but we just missed them – they showed up back in the age of dinosaurs, or perhaps earlier than that. Or they came when the smartest primate was a lemur.

This gets interesting, though. A study by Charles H. Lineweaver, Yeshe Fenner, and Brad K. Gibson at the University of New South Wales back in 2004 examines the Galactic Habitable Zone, and looks at the distribution of stars that could have habitable planets over time as well as space.

Basically it finds that you get the center of the bell curve about 5 billion years ago for the origins of stars that would harbor life at all, and that gives a rough idea of where you’d expect civilizations to happen in time as well as space. If it takes around 4-5 billion years to get to a civilization, then you’d expect the bulk of intelligent civilizations to just be appearing now, give or take a half a billion years. Note that we got a figure of about 140 civilizations at any given instant; but if we take the bell curve approach we can see that they might spread out over quite a lot of centuries.

But what if most civilizations don’t last that long? This would say that even with a relatively narrow “peak” we’re still talking about time scales of hundreds of millions of years. Civilizations might have even passed through our solar system, and disappeared before we noticed. (Stephen Baxter’s novel Space gets into this possibility).

At this point one might invoke some kind of “great filter,” which destroys civilizations before they get a chance to develop. Baxter’s book (and a that gamma-ray bursters sterilize huge chunks of the galaxy every so often in a cosmic “reboot.” Another idea is that civilizations that are prone to colonizing (like ours) tend to destroy themselves thorough overuse of resources. More outlandish theories are that there’s some race of killer robots that gets rid of the competition.

I don’t feel that any of these are particularly helpful, because they rely too much on assumptions that may or may not be right. I would argue that we should go with the principle of parsimony – the simplest idea. And that is that civilizations are simply rare in space, or rare in time.

Even a “tight” grouping of aliens in time has a spread that is as long as multi-celled animals have existed on Earth. Since we don’t see anyone else, that would appear to show aliens are rare enough that in any given span of a century or less we aren’t going to see them.

If civilizations are rare – so rare that we might be the only ones in our galactic neighborhood, then I’d argue it’s doubly important that we think in the long term, that we act to make sure we go on surviving, even into deep time. That’s going to take a lot of work and dare I say it, social change. With luck, though, we’ll do it — if a meteor doesn’t smack us first. I suspect a dinosaur might have something to say about that.

In a previous post I addressed the issue of why we might have lots of extraterrestrial civilizations nearby and never see them. It was a stab at addressing the Fermi Paradox, which is basically asking, if there are aliens out there, why don’t we see any evidence of them?

In that one I was speaking about civilizations at roughly our level of technology. By that I mean that they use radio, that they haven’t got anything we’d necessarily describe as “magic” and they haven’t got some way around the speed of light limit.

But let’s think about civilizations that are way ahead of us. Imagine a species with a million- or billion-year head start at having a technical civilization. We literally can’t imagine the kinds of thing they could do, anymore than a member of Homo erectus could figure out how an iPad works. We wouldn’t even have the language for their technologies.

With capabilities that impressive, those hypothetical beings ought to be able to do things that are pretty spectacular. Like re-engineer galaxies, or at least, build Dyson spheres – huge structures that surround a parent star and create living space on the whole thing, making use of all of the star’s energy. So why don’t we see a bunch of weird-looking stars that are obviously engineered?

It turns out that there’s a number of big limitations on building structures like Dyson spheres. That doesn’t mean it’s absolutely impossible (in the physical sense) to overcome them. What we find though, is that if you have the ability to build a Dyson sphere in the first place, you likely as not don’t need it anymore.

So, what’s a Dyson sphere? Back in 1960 Freeman Dyson, a theoretical physicist and mathematician, first proposed the idea of using a sphere of satellites surrounding a star to capture all of the star’s energy for use by whatever civilization built it. He wasn’t proposing as solid shell — such a structure is not mechanically possible, no matter what the technology.

A solid shell has two major problems: First there is drift. A Dyson sphere is still subject to the local sun’s gravity and is being pulled inward. But there’s no net force on the star in the center because there’s an equal amount of matter on all sides of it. That means that the star in its center will drift, and eventually punch a hole in the sphere unless the sphere has either some way of propelling itself or repelling the star inside. The other problem is stress. A shell of anything that was completely solid would act like two attached domes. At any point the weight of the domes would compress the material. Imagine a dome that is 93 million miles high, under the weight of the gravity one would feel from the sun at that distance. That’s a lot of force when applied to a structure that big. There isn’t any material anyone knows about that could handle that.

A Dyson sphere is also pretty useless as living space. Standing on the inner surface of a Dyson sphere would result in you falling “up” towards the sun in the center of it (if very slowly at first). The only way to prevent that would be to rotate the sphere, but then the “gravity” inside wouldn’t be constant. It would be greater towards the equator and less towards the poles (eventually becoming zero at the pole itself). So your useful living space would be limited to a band around the equator.

All this is to note that the idea of looking for the signature of solid Dyson spheres doesn’t make a lot of sense. If you can replicate and gather enough material to make one, there’s a lot of other stuff you can do that’s more useful.

Far better is the Dyson ring configuration and its variants. This involves building a huge ring around your local sun and having a swarm of satellites in many, concentric but differently-oriented rings. This still presents pretty big dynamical problems – you’d need some way to keep the satellite formation stable — but at least it’s more feasible and sensible if you want to catch as much energy from a star as possible and provide living space to go with it.

The thing is, at interstellar distances you won’t necessarily see them. A ring won’t affect the light from a star at all unless it is right in your line of sight, and the odds of that are very, very tiny. A warm of satellites wouldn’t affect the light from a star that much either. From a great distance the star’s light might look dimmer, but it would be hard to distinguish the effect from that of interstellar dust and a big swarm of asteroids (dust clouds and the like are pretty common).

That said, a sensitive enough search would show sun-like stars with an anomaly: the amount of infrared radiation would be larger than expected if a Dyson swarm were absorbing and re-radiating energy. Thus far nobody has seen anything like that, but unless your swarm were very, very closely packed it wouldn’t be easy to pick up.

Again we have the same issue as with radio emissions: there might be a Dyson ring-capable civilization close by. But we’d never notice because their ring just happens to be oriented the wrong way.

What about the really big project, like galacto-engineering? That’s still something of a problem because of the time constraint on life. That is, there’s only so far back in the history of the universe you can go before you can’t have life at all, because the relevant chemicals were not formed yet in the cores of stars.

This is important because any galactic engineering project is going to take millions of years to do – the speed of light limit ensures that. If you were re-engineering a cluster, it would be several million, possibly a billion, years before the new shape or color of the galaxies involved was visible.

The earliest dates for life in the universe are under some debate. The earliest estimates for life to emerge would be a mere 100 million years after the Big Bang, some 14 billion years ago. Avi Loeb, an astrophysicist at Harvard, thinks that because the cosmic background was at that point a comfortable 70 degrees or so, you wouldn’t even need stars to shine for life to form on planets out in the universe, and there might have been enough elements heavier than lithium to form them. It seems unlikely, though, that you could get intelligent life that way, even if he is correct.

Given that it seems to take billions of years to get to intelligent beings, that would point to the earliest civilizations appearing at least a few billion years after the Big Bang, On Earth 4.5 billion years went by before tool-using creatures appeared. A planet that formed in the earlier universe might have taken less time – or longer. But let’s be optimistic and assume it took only a couple of billion years to have the first smart beings.

That means they would have civilizations 10 billion years old by now. We can see most galaxies out at least that far. Many galaxies are an order of magnitude closer than 10 billion light years. If these beings were engaged in some galactic re-shaping project, we should see the effects on galaxies like Andromeda, which is only 2 million light years away.

The thing is, we don’t know what to look for. I mentioned earlier that we might not have the language to even express what these super-beings are doing. It is also far from clear we’d be able to see their effects on other galaxies for the same reason that you can’t see the largest human structures on Earth without a close look. Humans have wreaked profound changes in the Earth’s atmosphere and biosphere, but an observer looking at us from afar wouldn’t be able to pick up those changes.

In a similar vein, it’s possible the aliens did some pretty major work on Andromeda. But since they didn’t do anything obvious to us, visible on a scale a hundred thousand light years across, there’s no way to tell. Maybe they re-engineered every single planet in their galaxy to have a great big “Hi we’re here” sign — we would never see it. Perhaps they are drawing energy from Andromeda’s magnetic fields — again, there would be few ways for us to tell.

All this sounds pretty bleak for finding aliens. But Ethan Siegel, a former professor at Lewis & Clark College in Oregon and a theoretical cosmologist. He said looking for signatures of artificial elements might be one sure fire method of detecting aliens. Technetium is one such element. It has no way to form naturally, so if you find it in the emission line of a planetary atmosphere, you’ve found your aliens. Loeb suggests something similar – look for chemicals in planetary atmospheres that are artificial, or largely so. Essentially, see if the aliens are polluting.

Another method Siegel suggests is to look at the planets directly. Build a telescope big enough and you could theoretically pick up artificial lights from the nigh side of a planet. We are just approaching the ability to do that now, so in the near future we’ll get a better idea of how rare or common we are.

In a future post I’ll talk about the real meat of the paradox: why aliens aren’t approaching in spaceships – or don’t seem to be.

Apropos of a bit in Wait But Why? About why there are (apparently) no other intelligent beings that we can see in the universe, there were a couple of things I wanted to check out. One was the average distance between civilizations. That is, about how far away the nearest group of aliens ought to be. The other was thinking through whether we’d even notice they were there.

Now a caveat: I am not an expert on extraterrestrials, or even astronomy. I am a guy who took some physics, and knows a little math, and who has had the occasional back-and-forth about this in other corners of the Internet. If there’s an expert out there who can tell me why I am way off, please let me know.

So, on the first point there are a couple of ways to approach it. One is to look at the number of planets that the Kepler mission discovered around other stars.

The Planetary Habitability Laboratory has one way of looking at it – they took the number of stars with anything like an “Earth like” planet around it in the solar neighborhood. A lot of those stars won’t be like the sun at all; they will be reddish dwarf stars. Such stars are nearly impossible to see with the naked eye, and they are much less massive than the sun. They can be, however, more stable in the sense that they live a lot longer.

That said, let’s take their estimate as a given. Up to 160 habitable worlds within about 33.6 light years sounds pretty good. So how far away from each other would they be?

Assuming a 33.6 light year radius, that works out to a sphere of about 159,000 cubic light years. We divide that by 160. So each planet is in a sphere of roughly 993 cubic light years, which we can round up to 1,000, or a cube 10 light years on a side. If we were more exact about the volume of a sphere we’d get a radius of about 6.1 light years, so let’s take an average and call it 7.5 to 8 light years on average. That’s about twice the distance to Alpha Centauri, and it’s close enough that radio communication is actually feasible, since the time lag isn’t so long – a message would take about 15 years to get a response.

But now we get to a harder problem. Why isn’t there anyone there? And that means looking not only at how many planets there are but how many are habitable and how many actually develop life.

There are no other examples of life except Earth (so far). We can, though, extrapolate a bit. Mars is dry and cold now, but it might have been wetter and warmer in the distant past. Jupiter’s moon Europa has possibilities, too. So let’s assume that any system with a habitable planet has more than one, call it two. That means 320 habitable worlds in the neighborhood, which also sounds good.

Not every planet will develop life. That’s the major bottleneck, as it were, to finding intelligent beings. There’s a lot of theories about such bottlenecks and why they might or might not occur, and I’ll get into those later. But for now, let’s stick to the numbers we have. Life developed on Earth pretty quickly, as these things go, within a billion or so years – the earliest evidence is 3.5 billion years back at least. That sounds like a long time but it is only a small percentage of the time Earth has been around, about 4.5 billion years.

So looking at our own planet at least it looks like life takes hold as soon as it can. There’s some scientific controversy about the exact mechanism, but the short answer is that whatever drives life to happen, it didn’t wait long – basically as soon as water was a liquid and the temperature dropped enough that organic molecules would hold together, you had life.

But now we get to the kind of life that we think of as resembling us. That took a lot longer. From 3.5 to 1.5 billion years ago (give or take 200 million years), there wasn’t anything on the planet that even had a cell nucleus. Colonies of single-celled organisms seem to have appeared about 2.1 billion years ago, but multicellular life that has specialized cells doesn’t appear until 600 million years ago or thereabouts (the Ediacaran fauna). Now, granted, multicelled animals probably existed before then, since we only know about the ones that leave fossils. Even so, that means in the history of the planet, while there was biomass around, most of the time it’s been algal mats and bacteria. Multicellular life has only been around for some 15-20% of the planet’s history.

That may mean the leap from single-celled to multicellular life isn’t one that happens very often. It might mean that most planets that are near the mass of the Earth and in the habitable zone have life but the most intelligent creature is a lichen.

So let’s come up with a reasonable estimate for how often life gets to be multi-cellular. Assuming our number of habitable planets in a given system averages to two, we’ll assume that half develop life and half of those make the jump past algal mats and germs. That gets us 80 planets in the 33.6 light year radius we started with.

Once past that point, though, you need to develop intelligence, and you need to develop tools, and you need a way to communicate over interstellar distances (or at least be visible).

So far technological intelligence has developed only once on Earth – that is, in primates. We could argue all day about how smart dolphins are, but they don’t build radio telescopes, so any intelligent sea life out there probably won’t be visible. (Water is an excellent shield for high-frequency transmissions, so even if they built radios they wouldn’t be transmitting in a band we could hear). The fact that only one lineage out of thousands got to tool-making does not bode well.

What are the odds then? One percent? Ten percent? Going by a number-of-species argument (remember that millions of species have come and gone) it would be less than one percent, and even counting by whole families (in the zoological sense). So let’s assume one percent make it to a technical civilization, which is probably high.

Now we’ve reduced the number of planets in the neighborhood with intelligent life to about 0.8.Which is about what we observe. There’s just us – or rather, we’re the only ones anyone else could see with a radio telescope. If the percentage is 0.5 percent, then the nearest civilization will be (on average) 60 light years away or more.

This is important when thinking about how we might detect other civilizations. The most powerful signals we ever sent out – and those were not omnidirectional – were those from early-warning radar during the Cold War. An alien civilization might pick those up if they happened to be in the beam, but even that is only out to tens of light years – call it 100 at the outside. If the ETs are more than a few tens of light years distant then we’d never see them at all even if we happened to be right in the beam.

Aliens using AM or even low-frequency FM radio wouldn’t be heard (and neither would we), because AM signals don’t penetrate the ionosphere. To get an interstellar signal you need to at least be in the UHF television range. (Any planet with life in the first place is pretty likely to have an ionosphere, because gases in the atmosphere get ionized by solar radiation).

A paper by John Billingham and James Benford on the ArXiv (link here) outlines the difficulty of hearing “leakage” transmissions, which is what we are talking about. They note that the Square Kilometer Array can pick up anything within about 650 light years by looking at how much energy it produces against the background — but deciphering of the signal itself is much harder, because it is still faint. Their paper focused on the costs of building a radio telescope that could pick up other civilizations, but the main point is that absent some technology and physics we haven’t heard about, while aliens who happened to point a radio telescope in our direction might figure out something is there, “I Love Lucy” reruns wouldn’t be visible.

There’s also an old graph from the SETI projects from NASA here. Look at the effective power of the transmitters and the sensitivity of the sky searches (the vertical lines). What it shows is that if you used the biggest radio telescope in the world — Arecibo, which is some 300 meters across — as a radar array you could be detected within 1000 light years, if an observer were looking right at it. Otherwise, more than 30 or so light years out you’d never see the transmission. UHF TV wouldn’t be heard at all, even by an Arecibo-sized receiver staring right at the relevant star.

What about more advanced aliens? That might actually be an even bigger problem. Digital signals are fast becoming the way we communicate – the old loud radar and RF transmissions are becoming passé. We have used radio for about 100 years, and that means anyone listening for us has to hit that window. The same applies in reverse.

This gets into something else about finding alien life forms: the issue of time. Picture an alien civilization that is situated 200 light years away. They do exactly what we did, and invent radio. They broadcast, and 100 years later they invent the Internet.

If they invented radio 300 years before we did, in say, 1600, the first signals we could hear would arrive around 1830 or 1840. (Assuming it took them 30 years to hit a golden age of radio, like we did). That means our window to hear them would have ended in about 1950 – if we even knew to listen. After that, no dice. The digital signals would be almost impossible to pick out from the background, even if they were loud enough.

Think now about the idea that the distances aliens are likely to be will be random and the galaxy is very, very big. For us to pick up an equivalent civilization they would have to be precisely placed in a sphere of about 200 light years. The whole galaxy is thousands of times that size. A civilization too close hasn’t invented radio yet (or not far enough in the past for us to hear). Too far and we missed them.

Now, I want to be clear: this is not to say that there is no intelligent life. I am offering a set of reasons why even if there were people living right nearby they would be very, very hard to see. There could be a half-dozen civilizations within 100 light years, and unless they did some major stellar engineering project like a Dyson sphere or beamed a signal right at us, we might never know.

Maybe a better way to phrase the Fermi paradox is to ask not why we don’t see anyone, but how we can improve the detection methods to see them at all. That may be a bigger project than lots of people realize — but I think it’s certainly worth doing.

]]>https://jesseemspak.com/2014/12/29/is-the-fermi-paradox-really-a-paradox/feed/1jesseemspakThe Traveler…https://jesseemspak.com/2013/10/29/the-traveler/
https://jesseemspak.com/2013/10/29/the-traveler/#respondTue, 29 Oct 2013 14:08:04 +0000http://jesseemspak.com/?p=53Continue reading →]]>I called this blog Traveler’s Tales. It’s a bit of a homage to Carl Sagan. His book Cosmos was one of the things that made me see science could be poetic, and for that I wish I had thanked him when he was alive.

I travel a bit, and I write about science. Where possible I like to combine the two, but not always. I’m interested in places, and how those places interact with people, and sometimes how the world — the things we like to call natural laws — shape that.

I also live in one of the great cities of the world, so oftentimes I will be writing about that too. One of the things about living in New York is that while it’s symbolic — cue up Frank Sinatra — but it is one of those places that after you’ve lived here a while, sometimes it’s hard to imagine yourself anywhere else.

That’s one of the things about the traveler. That person isn’t just bringing tales back home from elsewhere, they bring tales of home to other places. When I write about science I do the former, and when I write about New York I do the latter, and with any luck I’ll do it reasonably well.

]]>https://jesseemspak.com/2013/10/29/the-traveler/feed/0jesseemspakHalloween, Lou Reed, and Storieshttps://jesseemspak.com/2013/10/29/halloween-lou-reed-and-stories/
https://jesseemspak.com/2013/10/29/halloween-lou-reed-and-stories/#respondTue, 29 Oct 2013 13:04:08 +0000http://jesseemspak.com/?p=41Continue reading →]]>I live in New York. It’s the city that you can’t imagine Lou Reed without – his being here, from when he played the clubs to the exhibits of his photographs. Listening to his music was a kind of snapshot of a place that I unabashedly aspired to be in — and to an extent, still do.

Lou Reed wasn’t just about great music. He told stories. When I first heard a full album of his I was a DJ for my college radio station in 1989. In the pile of CDs – then a new technology – was the album New York. And when I heard it I thought, “I want to write stories like that.” Not songs. Stories.

Concept albums hit their heyday at least a decade before New York hit the shelves. Even then they were rare and strange beasts, and in an age of sampling and mp3 files may be even more so. New York is often ranked in the bottom half of Lou Reed’s oeuvre, yet to me he still ranks with Carl Sandburg among the great poets of the city. And also someone who spoke up for the people who other folks would just as soon stayed in the closet.

And as Halloween is upon us, I want to talk a bit about one of those stories.

There’s a downtown fairy singing out “Proud Mary”
as she cruises Christopher Street
and some Southern Queen is acting loud and mean
where the docks and the badlands meet

People of a certain age might remember the fear that once came with the term “AIDS.” Before modern (and still insanely expensive) drugs were available, there were few diseases that could scare a 20-something as much. I’d had blood transfusions previously, before the blood supply was cleaned up. I remember the jolt when a nice clinic worker asked about it during a blood drive. I had that nagging voice at the back of my head – what will the test results be? For LGBT people – especially those in the closet — the situation was far, far worse.

Many still had all kinds of weird ideas about how it was transmitted. Gay people I knew in college were still trying to get across that people without HIV posed more danger to the infected than the other way around. Even a decade later, I still had someone ask me if it was safe to have dinner with an HIV-positive friend of mine.

In New York City, the death toll was mounting. And in the arts community especially, there were funerals. A lot of them, though a lot of the time nobody said what the cause of death was. Some were famous names like Robert Mapplethorpe and Alvin Ailey. But most weren’t. They were just local actors or musicians or artists who were struggling to get by.

Lou Reed’s songs often touched on the gay and transgendered – “Walk on the Wild Side” was only the best known. Lou wrote about the people at the margins, the nooks and crannies of a city that produced some great talents. The Village was one of those places. Given the neighborhood’s status as an emotional center for many in the city’s LGBT community, it should be no surprise that Reed chronicled the hit the neighborhood was taking. And he chose the Halloween Parade, a Greenwich Village institution, to show it.

There’s no Peter Pedantic saying things romantic
In Latin, Greek or Spic
There’s no Three Bananas or Brandy Alexander
Dishing all their tricks
It’s a different feeling that I have today
Especially when I know you’ve gone away

Reed rattles off the names, sounding easy as you please – each one was a friend, a lover, a son or daughter. On Halloween you show the pieces of yourself that aren’t allowed the rest of the time – is there a better metaphor for so many that were still in the closet then?

And yet the parade itself was never a “gay” event. It was just people in the neighborhood having a blast. Sure it grew, but how many local parades showcase the talents of puppeteers? By the late 1980s it was one of the biggest parties in the city. That’s why the event has survived – after Hurricane Sandy, people gave money on Kickstarter to make sure it happened again this year. Tourists come, sure, but it’s also an event for the people here, by the folks that live here.

There’s the Born Again Losers and the Lavender Boozers
and some crack team from Washington Heights
the boys from Avenue B and the girls from Avenue D
Tinkerbell in tights

And that’s why “Halloween Parade” is so moving. Give it a listen. Put yourself in the shoes of the community struggling with a crisis and facing the indifference, even fear, of the surrounding city. A community that said they’ll put on a show anyway, and invite everyone, because no matter how bad things got it was never a reason to tell people they weren’t welcome.

It’s all history, one might say. The Village isn’t the Village anymore, not like it was in the 1980s and early 90s. And even then, it was disappearing. New Yorkers didn’t know what it would become, though we knew the kind of artist Lou Reed represented wasn’t likely going to be part of the neighborhood’s future. The Village has been a home to artists and bohemians of various stripes for a century, and I am sad to see that fade away.

So I will stand on Sixth Avenue this year, and wave to the people who wear their wildest fantasies on the outside for one night. And I’ll be thinking of the man who once wrote the eulogies for denizens of the old neighborhood. It’s not his best song, but it doesn’t have to be.